1. Field of the Invention:
The present invention relates to a transmission unit for a hybrid vehicle. The hybrid vehicle is provided with an internal combustion engine and a motor/generator (a motor that functions as a generator), an output torque of these drive sources being transmitted to a variable gear shift unit to achieve a vehicular run driving force by either or both of the engine and the motor.
2. Description of the Related Art:
A Japanese Utility Model Registration Application Publication No. Heisei 2-62157 published on May 9, 1990 exemplifies a previously proposed housing structure of a transmission unit for a hybrid vehicle.
The previously proposed housing structure includes a first casing and a second casing, mutually facing surfaces of these first and second casings being joined in a flange structure. The mutually facing surfaces are only in outer peripheries of the first and second casings.
However, in a case where the transmission unit of the hybrid vehicle in which the motor (motor/generator) is incorporated, a motor chamber needs to be installed within the above-described joined casing of the transmission unit.
In this case, it is necessary to keep the motor chamber dry (under a state wherein oil is not lubricated).
It becomes difficult to maintain a seal characteristic against a wet chamber in which a transmission is housed. In addition, if a motor housing were additionally installed into the transmission unit housing so that the motor chamber can be defined as the dry chamber, this would introduce an increase in the number of parts.
It is therefore an object of the present invention to provide an improved housing of a transmission unit for a hybrid vehicle with a dry chamber having a high sealing ability and in which a motor (a motor/generator) is housed without introduction of the number of parts.
The above-described object can be achieved by providing a hybrid vehicle comprising: an engine (2); a clutch (11); a motor (15); a transmission (13) comprising an input axle that is disengageably engaged to the engine by the clutch and on which the engine, the clutch, and the motor are serially arranged and an output axle which is arranged in parallel to at least the motor; and a unit housing of the transmission comprising at least a first housing (42) and a second housing (41), the first housing comprising: a first partitioning wall (46) elongated in a radial direction of the transmission to define a first dry chamber and a second dry chamber, both of the first and second chambers inhibiting an entrance of a lubricating oil; and a third partitioning wall (70) elongated in an axial direction of the transmission to define the first and second dry chambers together with the first partitioning wall and to define a second wet chamber allowing the entrance of the lubricating oil, the second housing comprising: a second partitioning wall (45) elongated in the radial direction thereof to define a first wet chamber allowing the entrance of the lubricating oil; and a fourth partitioning wall elongated in the axial direction to define the second dry chamber and the second wet chamber together with the second partitioning wall, a first seal flange surface being formed on an end surface (72) of the third partitioning wall of the first housing and being on the same plane as an end surface of an outer periphery of the first housing, a second seal flange surface being formed on an end surface of the fourth partitioning wall and being formed on the same plane as an end surface of an outer periphery of the second housing, and the first housing being joined to the second housing by the first and second seal flange surfaces.